add support for 1D numerical attributes in mo_netcdf and others

This is needed to be able to read some attributes like valid_range from a netCDF file corresponding to CF conventions, as also set in the netcdff docs.

I also updated the CMakeLists.txt file with some updated file for detecting netCDF-C and netCDF-Fortran (here. It requires an environment variable pointing to the netcdf installation though, if it is not found by find_library.

I fixed some bugs in mo_sce.f90 raised by the NAGfor compiler.